Machine tool cutoff slide

ABSTRACT

A machine tool for use when parting off a component from a barstock using a parting off tool and comprising a pusher member engageable with the component and arranged to apply a lateral force to the component to shear the component from the barstock when the parting off tool has machined to a predetermined depth the bridge of material forming the connection between the component and the barstock.

United States Patent Jack A. Hazel Northolt, Enfland Nov. 19, 1968 May25, 1971 C.A.V. Limited Warple Way, Acton, London, England InventorAppl. No. Filed Patented Assignee MACHINE TOOL CUT-OFF SLIDE 5 Claims, 2Drawing Figs.

Int. Cl. B23b 5/14 Field of Search 82/1 .4, 47,

References Cited UNITED STATES PATENTS 2,627,107 2/1953 Malco PrimaryExaminer- Leonidas Vlachos Attorney-Holman and Stern ABSTRACT: A machinetool for use when parting off a component from a barstock using aparting off tool and comprising a pusher member engageable with thecomponent and arranged to apply a lateral force to the component toshear the component from the barstock when the parting off tool hasmachined to a predetermined depth the bridge of material fonning theconnection between the component and the barstock.

MACHINE TOOL CUT-OFF SLIDE This invention relates to a machine tool andin particular to a machine tool for parting off a component frombarstock using a parting off tool having a cutting edge formed at itsleading edge, the latter being inclined to the direction of feed of thetool.

The operation of a conventional parting off tool is to cut the portionof the barstock adjacent to the component, to the shape of a truncatedcone which gradually decreases in size as machining proceeds untiltheoretically, the component breaks off at the apex of the cone, theapex being adjacent to the component. In practice however, the base ofthe cone usually shears off from the barstock due to the fact that thecutting load presented by the tool is transmitted via the base of thecone and the result is that the component becomes detached from thebarstock along with the cone and any swarf which is attached thereto.This means that another operation must be performed on the component toremove the cone.

v A machine tool for the purpose specified comprises a pusher member forengagement with the component, means operable to move said pusher memberinto engagement with said component and means for applying a force tothe pusher member which is transmitted to the component as a lateralforce, the lateral force increasing until the component is sheared fromthe barstock.

One example of a tool in accordance with the invention will now bedescribed with reference to the accompanying drawing in which:

FIG. 1 shows the conventional parting off operation and FIG. 2 shows theapparatus additionally provided.

Referring to FIG. 1 of the drawing there is illustrated a work spindle laccommodating barstock 11 to which is secured a component 12 which hasjust been machined. The parting off tool is indicated at 13 and isprovided with an inclined cutting edge 14. In operation the parting offtool is moved towards the axis of rotation of the barstock and componentand a portion of the barstock adjacent to the component is machined totruncated conical form. The size of the resulting cone 15 diminishes asmachining proceeds, until theoretically the component breaks off fromthe barstock at the apex of the cone. In practice however the coneusually shears at its base from the barstock and remains attached to thecomponent together with any swarf which is attached to the cone. Thereason for this is that the cutting load imposed by the tool istransmitted through the base of the cone which eventually shears. Thisis accentuated by the fact that the machining speed progressivelyreduces as the parting off tools moves towards the axis of rotation.

The presence of the cone together with any swarf on the componentpresents a problem since a further machining operation or finishingoperation is necessary to remove the cone and this adds expense to theproduction of the com ponent and is generally inconvenient particularlywhere automatic feed systems are utilized and feed the component toadjacent machines.

The principle of the present invention process and tool is to cause thecomponent to be sheared from the cone before the latter is sheared fromthe barstock. With the component removed the matching process iscontinued to remove the cone from the barstock.

The apparatus as seen in FIG. 2 comprises a pusher member 16 which isshaped to engage the component adjacent to the end thereof where thecone will be produced. The member 16- is mounted upon one end of a rod17 which is movable axially within a body member 18. The rod 17 isbiased away from the component by the action of a coiled compressionspring 19 and projecting from the rod is a peg 20 slidable within a slotformed in the body member 18. The peg is engaged by the forked end of alever 21 pivotally mounted upon the body member at 22. The body member18 is adapted to be clamped to the slide which carries the parting offtool 13.

Secured to the fixed part of the machine is an abutment block 23 uponwhich is slidably mounted a movable abutment block 24. The movableabutment block is connected to a screw-threaded rod 25 which'extendswith clearance through an end plate 26 of the fixed abutment block 23and a coiled compression spring 27 is provided intermediate the plate 26and an adjustable collar 28 mounted upon the rod 25. The rod 25additionally carries a stop 29 to limit the movement of the movableabutment block under the influence of the spring 27.

The movable abutment block in its upper surface, is provided with arecess having an end wall 30 for cooperation with a further peg 31projecting outwardly from the lever 21.

-In operation, at the start of the parting off operation the peg 31 isclear of the end face 30 of the recess, but as the parting off operationproceeds the peg 31 moves into contact with the end face 30 and thismoves the pusher member 16 into contact with the component. Furthermovement of the slide carrying the parting off tool causes the lever 21to be moved in an anticlockwise direction about its pivot 22 and thisimparts move ment to the movable abutment 24 against the action of thespring 27. In addition, a lateral force is applied by the pusher memberto the component. As machining further continues a point is reached atwhich the connection of the cone 15 to the component is so thin that theconnection is sheared by the action of the lateral force imposed by thepusher member. As soon as the shearing action starts to occur the forceexerted by the spring 27 effects movement of the movable abutment membertowards the position in which it is shown and this movement is magnifiedby the action of the lever 21, the pivot point of which is closer to thepeg 31 than to the peg 20. During this movement the pusher member movesrelative to the parting off tool. Thus the component is sheared from thecone quickly and the break off is comparatively clean.

The initial position of the movable abutment block 24 determines theinstant at which the pusher member starts to apply a lateral force tothe component and this point can be detemiined by adjustment of the stop29 upon the rod 25 The force exerted by the spring 27 can be adjusted bymeans of the adjustable collar 28,'and in the event that the parting offtool breaks during the operation the resulting movement of the pushermember relative to the body member 18 is accommodated by compression ofthe spring 27 so that there will be no damage to the machine. Thepurpose of the spring 19 is to return the pusher member 16, the rod 17and the lever 21 to their original positions after the parting offoperation has been completed.

I claim:

1. A machine tool comprising a frame, means for rotatably supportingbarstock, a movable slide carried by said frame, a parting off toolcarried by said slide, said parting off too] having a cutting edgeinclined to the rotary axis of said barstock and the slide being movableto cause the parting off tool to sever the barstock, a pusher membercarried by said slide for engagement with the portion of the barstock tobe served, said pusher member being movable relative to the parting offtool, a part secured to the movable slide, a lever pivotally mountedupon said part means pivotally connecting one end of said lever with thepusher member pin means at the other end of said lever, an abutmentblock, said abutment block being connected to said frame through theintermediary of resilient means, the arrangement being that after thepusher member has engaged with the portion of the barstock to be servedthe resilient means is tensioned during continued movement of the slide,until the lateral force applied to the component is sufiicient to causeshearing of the component from the barstock.

2. A machine tool as claimed in claim 1 in which the arms of said leverare of unequal length, the shorter arm being between the pivot of thelever and said other end thereof whereby as the component barstock issheared the pusher member moves relative to the parting off tool.

3. A machine tool as claimed in claim 2 in which the initial position ofthe abutment block prior to movement of the lever is adjustable.

4. A machine tool as claimed in claim 3 in which the pusher member isslidably mounted on said part and is spring loaded in a direction awayfrom the component.

5. A machine tool as claimed in claim 4 in which the spring loading thepusher member is weaker than the spring constituting said resilientmeans.

1. A machine tool comprising a frame, means for rotatably supportingbarstock, a movable slide carried by said frame, a parting off toolcarried by said slide, said parting off tool having a cutting edgeinclined to the rotary axis of said barstock and the slide being movableto cause the parting off tool to sever the barstock, a pusher membercarried by said slide for engagement with the portion of the barstock tobe served, said pusher member being movable relative to the parting offtool, a part secured to the movable slide, a lever pivotally mountedupon Said part means pivotally connecting one end of said lever with thepusher member pin means at the other end of said lever, an abutmentblock, said abutment block being connected to said frame through theintermediary of resilient means, the arrangement being that after thepusher member has engaged with the portion of the barstock to be servedthe resilient means is tensioned during continued movement of the slide,until the lateral force applied to the component is sufficient to causeshearing of the component from the barstock.
 2. A machine tool asclaimed in claim 1 in which the arms of said lever are of unequallength, the shorter arm being between the pivot of the lever and saidother end thereof whereby as the component barstock is sheared thepusher member moves relative to the parting off tool.
 3. A machine toolas claimed in claim 2 in which the initial position of the abutmentblock prior to movement of the lever is adjustable.
 4. A machine tool asclaimed in claim 3 in which the pusher member is slidably mounted onsaid part and is spring loaded in a direction away from the component.5. A machine tool as claimed in claim 4 in which the spring loading thepusher member is weaker than the spring constituting said resilientmeans.